Interactions of Streptococcus iniae with phagocytic cell line.

Streptococcus iniae has become one of the most serious aquatic pathogens in the last decade, causing large losses in wild and farmed fish worldwide. There is clear evidence that this pathogen is capable not only of causing serious disease in fish but also of being transferred to and infecting humans. In this study, we investigate the interaction of S. iniae with two murine macrophage cell lines, J774-A1 and RAW 264.7. Cytotoxicity assay demonstrated significant differences between live and UV-light killed IUSA-1 strains. The burst respiratory activity decreased to baseline after 1 and 4 h of exposure for J774-A1 and RAW 264.7, respectively. Immunofluorescent and ultrastructural study of infected cells confirmed the intracellular localization of bacteria at 1 h and 24 h post-infection. Using qRT-PCR arrays, we investigated the changes in the gene expression of immune relevant genes associated with macrophage activation. In this screening, we identified 11 of 84 genes up-regulated, we observed over-expression of pro-inflammatory response as IL-1α, IL-1ß, and TNF-α, without a good anti-inflammatory response. Present findings suggest a capacity of S. iniae to modulate a mammalian macrophages cell lines to their survival and replication intracellular, which makes this cell type as a reservoir for continued infection.

Poly(ε-caprolactone) films with favourable properties for neural cell growth.

The regeneration of brain tissue is one of the major challenges in regenerative medicine due to the lack of viable grafts to support the re-growth of functional tissue after a traumatic injury. The development of biocompatible and biodegradable structures with appropriate morphology for the interaction with neural tissue is required. The objective pursued in this work is to develop a biodegradable 2D scaffold structure for neural tissue engineering. Poly(ε-caprolactone) (PCL) was the selected material due to its biocompatibility and biodegradability in the long term. PCL (15%w/w) was dissolved in N-methylpyrrolidone and the film was fabricated by phase inversion casting technique employing ethanol and isopropanol as coagulation baths. The physical structure, morphology and topography of the flat scaffolds were characterized using different techniques. The two different scaffolds presented homogeneous structure with high porosity (higher than 85%), contact angles higher than 90(o), high roughness (Ra> 0.6 µm) and superficial pore sizes of 0.7 and 1.7 µm, respectively. Permeance tests showed high water permeabilities (~350-590 mL m(-1) bar(-1) h(-1)) indicative of promising nutrients supply to the cells. Finally, in vitro human glioblastoma cells cultures after 48 hours showed good cell attachment, proliferation and penetration in the scaffolds. Detailed evaluation of the interaction between the surface morphology and the properties of the scaffolds with the cell response has been done. Thus, the PCL films herein fabricated show promising results as scaffolds for neural tissue regeneration.

Rhodococcus equi human clinical isolates enter and survive within human alveolar epithelial cells.

Rhodococcus equi is an emerging opportunistic human pathogen associated with immunosuppressed people, especially those infected with the human immunodeficiency virus (HIV). This pathogen resides primarily within lung macrophages of infected patients, which may explain in part its ability to escape normal pulmonary defense mechanisms. Despite numerous studies as a pulmonary pathogen in foals, where a plasmid seems to play an important role in virulence, information on the pathogenesis of this pathogen in humans is still scarce. In this study, fluorescence microscopy and vancomycin protection assays were used to investigate the ability of R. equi human isolates to adhere to and to invade the human alveolar epithelial cell line A549. Our findings indicate that some R. equi clinical strains are capable of adhering, entering and surviving within the alveolar cell line, which may contribute to the pathogen persistence in lung tissues.